Spectral behavior and linewidth of (GaAl)As-GaAs double-heterostructure lasers at room temperature with stripe geometry configuration

Experimental studies have been made of the spectral change with excitation and the linewidth of room temperature (Ga Al)As-Ga As heterostructure lasers. The lasers with stripe geometry configuration show uniform near-field patterns and single axial mode operations in relatively wide ranges of current levels. Continuous output powers of several to 20 mW (from one facet) have been obtained under single axial mode operations at current levels below 500 mA. Experimental data on excitation-dependent spectral change indicate that the laser line is homogeneously broadened and the diffusion of the inverted population plays an effective role in the single-mode operation at room temperature. Observations of the interference fringes with a Fabry-Perot etalon having plate separations of the centimeter range revealed the frequency variation with time under continuous operation. Probably this effect is the reflection of a very large temperature coefficient of the laser frequency at room temperature, Full linewidths shown in the photographs of the fringes taken with exposure times of about 1 s were less than several hundred megahertz, which is compared with the theoretical estimate of a few megahertz at several milliwatts.